Diazoxide (INN; brand name Proglycem[1]) is a potassium channel activator, which causes local relaxation in smooth muscle by increasing membrane permeability to potassium ions. This switches off voltage-gated calcium ion channels, preventing calcium flux across the sarcolemma and activation of the contractile apparatus.

Diazoxide interferes with insulin release through its action on potassium channels.[citation needed] The efflux of potassium, as an effect of diazoxide, will lead to hyperpolarization of cell membrane that leads to decrease calcium influx. The low calcium will decrease the release of insulin. Therefore this medicine is not given to non-insulin dependent diabetic patients.